I just bought my first starter kit, the s.s. choice no 7. stealth, and im already on my 4th cartidge on the 2nd day. I only vaped 5 or 6 times, with about 15 puffs per session. These cartidges feel strong for about 2 or 3 times, then they get weak. Is this normal? I thought the cartridges were suppose to hold a half a pack?